Electrical switch assembly with improved printed circuit contact structure

ABSTRACT

An electrical switch wherein one or more contacts are provided on a first contact member which is resilient and is formed of a layer of electrically conductive material on a base layer of insulating material. This contact member is biassed into engagement with a second contact member when the switch is closed. The second contact member is preferably a similar resilient member which may be secured to one face of a supporting member. Resilient sheets from which a plurality of different contact members can be cropped are also disclosed.

United States Patent Rubenstein [4 Mar. 21, 1972 [54] ELECTRICAL SWITCHASSEMBLY WITH IMPROVED PRINTED CIRCUIT CONTACT STRUCTURE [72] lnventor:Leonard Rubenstein, 27 Chessington Court N3, London, England [22] Filed:Feb. 26, 1970 21 Appl. No.: 14,615

[30] foreign Application Priority Data Feb. 26, 1969 Great Britain..10,397/69 [52] U.S. Cl. ..200/11 R, 200/16 C, 200/166 PC ..IIOlh19/58, H05k 1/00 Field of Search ..200/11, 24, 28, 86 R, 86 A, 200/166F, 166 PC, 168 G, 16 C [56] I References Cited UNITED STATES PATENTS3,010,182 11/1961 Quinlan ..200/24X 3,036,165 5/1962 Kallin et a1..200/24X 3,089,923 5/1963 Wright ..200/166 PC X 3,188,407 6/1965Augerinos.... .....200/l66 F X 3,204,236 8/1965 Duris et al.... ..200/11 X 3,261,929 7/1966 Neff,.1r..... ....200/ll D 3,306,994 2/1967 Bassett..200/16 3,398,253 3/1967 Krakinowski ..200/86 R 3,509,360 4/1970 Miller..200/86 R X Primary Examiner.1. R. Scott Attorney--Delio and Montgomery57 ABSTRACT An electrical switch wherein one or more contacts areprovided on a first contact member which is resilient and is formed of alayer of electrically conductive material on a base layer of insulatingmaterial. This contact member is biassed into engagement with a secondcontact member when the switch is closed. The second contact member ispreferably a similar resilient member which may be secured to one faceof a supporting member. Resilient sheets from which a plurality ofdifferent contact members can be cropped are also disclosed.

8 Claims, 5 Drawing Figures PATENTEDMARZI m2 SHEET 1 [IF 2 45 ADHESIVEMiami Fla. 2

ADHESIVE INTERFACE INVENTm Leona rd R u bans: n

PATENTEDHARZ] I972 SHEET 2 BF 2 INVENTOR Leonavd Rubens+em BY WATTORNEYS ELECTRICAL SWITCH ASSEMBLY WITH IMPROVED PRINTED CIRCUITCONTACT STRUCTURE BACKGROUND OF THE INVENTION This invention relates toelectrical switches.

STATEMENTS OF THE INVENTION The present invention includes an electricalswitch wherein a pair of electrical contacts are respectively providedby relatively movable contact members, a first of the said contactmembers is resilient and comprises a layer of electrically conductivematerial'on a base layer of insulating material, the said contactmembers are biassed into engagement with each other when the switch isin a closed condition, and the inherent resilience of the first contactmember then serves to assist in maintaining the said contacts inengagement with each other.

Suitably, an area of electrically conductive material on the firstcontact member which engages the electrical contact on the secondcontact member when the switch is closed is raised relative to theremainder of the said conductive material.

The invention also includes, for use in making an electrical switch, aresilient sheet comprising a base layer of insulating material having onone side thereof a plurality of mutually spaced strips of electricallyconductive material, each strip having at a predetermined locationthereof a raised contact area of electrically conductive material, thesheet being readily cropped into a plurality of electrical contactmembers each containing one or more of the said strips.

The invention also includes, for use in making an electrical switch, aresilient sheet comprising a base layer of insulating material having onone side thereof a plurality of mutually spaced strips of electricallyconductive material, there being a break in each strip, the sheet beingreadily cropped into a plurality of electrical contact members, eachcontaining one or more of the said strips.

Suitably, the mutually spaced strips extend parallel with one another orare concentric arcs of a circle.

The invention also includes a method of making an electrical contactmember for an electrical switch from a resilient laminate ofelectrically conductive material and insulating material, which methodcomprises the steps of applying a masking material to the layer ofelectrically conductive material, removing the masking material frommutually spaced, parallel arranged areas of the laminate to expose theelectrically conductive material, removing the exposed electricallyconductive material by etching, removing the masking material from theremaining, mutually spaced, parallel arranged strips of conductivematerial, and forming a raised contact area on each of the said strips.

The electrically conductive material is suitably copper and theinsulating material is suitably mylar, fiber glass or polyester fiber.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described,by way of example, with reference to the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a first electrical switch according tothe invention;

FIG. 2 is a longitudinal section of a second switch according to theinvention;

FIG. 2A are resilient sheets from which the switch of FIG. 2 is made;and

FIGS. 3 and 4 are perspective views of further switches according to theinvention.

The electrical switch shown in FIG. 1 of the drawings is a rotary switchcontaining two relatively movable contact members l and 3, eachproviding a series of electrical contacts.

Contact member 1 is a resilient sheet comprising a series of parallel,mutually spaced strips 5 of copper on a base layer 7 of mylar.

The member 1 is formed from a laminate of copper and mylar by applying aresist or other masking material to the copper layer of the laminate andremoving the masking material from selected areas by a photochemicaletching technique. The exposed copper is then removed by the sametechnique to leave the above-mentioned strips 5 of copper.

A raised contact area 9 is formed on each copper strip 5 by embossing,these contact areas being aligned in a direction laterally of the copperstrips 5.

The second contact member 3 of the present switch is a rotary switchingmember formed by securing an adhesive backing on one surface of aresilient sheet 11 to a cylindrical supporting member 13. The resilientsheet 11 comprises predetermined areas 15 of copper on a base layer 17of mylar, and like the contact member 1 is formed from a laminate by aphotochemical etching technique.

To form the switch the contact member 3 is mounted upon a suitablesupport 19 which allows rotation about the axis thereof. The resiiientcontact member 1 is mounted in a clamp 21 which engages an elongatedsection of the element which extends parallel with, and is spaced ashort distance from, one edge thereof. Alternatively, the surface of thelayer 7 of contact member 1 may be provided with a self-adhesive backingby means of which the member is secured to a fixed support.

The clamped section of the contact member 1 extends parallel with theaxis of the member 3 and the raised areas 9 on the copper strips 5engage the cylindrical surface of the member 3 along a line whichextends parallel with the axis thereof. The arrangement of the resilientcontact member 1 and the rotary member 3 is such that the former isbiassed out of its natural, planar shape by engagement with the member3. The inherent resilience of the member 1 tends to urge this memberback towards its natural shape, thereby maintaining the member firmly inengagement with the rotary member 3.

The copper areas 15 on the rotary member 3 are so chosen that each metalstrip 5 on the resilient member 1 is electrically connected to one ormore of the remaining strips 5 when the member 3 assumes a predeterminedangular position. Electrical connections to the strips 5 are made bysoldering electrical leads 23 to parts of the strips which are disposedon the side of the clamp 21 remote from the raised areas 9.

Additional pressure to maintain the resilient member 1 in contact withthe rotary member 3 may be applied by causing a further resilient member(not shown) to engage the member 1. To provide an even pressure a slitmay be provided between each pair of adjacent strips 5 at the end ofmember 1 contacting the member 13.

In the present switch the resilient sheet 11 of the rotary member 3forms a single turn round the cylindrical supporting member 13, opposededges of the sheet 11 contacting each other to form a seam which extendsparallel with the axis of the member 13. In an alternative constructionthe sheet 11 forms a spiral along the cylindrical supporting member 13.

It is convenient for a manufacturer or user of electrical switchingapparatus to be able to construct a wide range of switches to suit hisindividual circuits from components supplied to him from componentmanufacturers. In the present instance this is achieved by supplying aresilient sheet comprising a series of mutually spaced, parallelarranged strips 5 of conductive material on a base layer 7 of insulatingmaterial. Each strip 5 is provided with a raised contact area 9, asdescribed above.

From such a sheet the manufacturer or user can readily cut out aplurality of individual contact members 1 each containing apredetermined number of strips of predetermined length. Likewise, themanufacturer or user can be supplied with a further preformed resilientsheet from which he can crop one or more sheets 11 for mounting on acylindrical supporting member 13.

FIG. 2 of the drawings shows a second switch according to the inventionin which a first, resilient contact member 27 is again formed of aseries of copper strips 29 on a base layer 31 of mylar. In this device,however, each strip 29 is formed with two raised contact areas 33 eachof which is aligned with a corresponding contact area on each of theremaining strips.

There are therefore provided two lines of contact areas which extendlaterally of the strips 29.

A second contact member 35 of the present switch includes a resilientsheet containing a series of parallel, copper strips 37 on a base layer39 of mylar, the thickness of each strip 37 and the spacing betweenadjacent strips respectively corresponding to the thickness and spacingof the strips 29 on the first member 27. The base layer 39 of theresilient sheet is adhesively secured to a planar face of a supportingmember 41 by means of a self-adhesive backing thereon.

Each metal strip 37 on the second contact member 35 is formed with abreak 43 of predetermined length at a predetermined location thereon.

To form the present switch the contact members 27 and 35 are arrangedwith the two series of copper strips 29 and 37 parallel with one anotherand with each strip 29 on the member 27 facing a corresponding strip 37on the member 35. The resilient member 27 is then bent slightly about anaxis perpendicular to the strips 29, thereby moving the raised contactareas 33 out of the plane of the member towards the second contactmember 35, and is engaged in the holder 45. The resilient member 27 isthen arranged with the contact areas 33 engaging the member 35 andbiassed thereby towards its natural planar shape. Holder 45 is engagedin grooved supports (not shown) which constrain movement thereof to thedirection of the arrows in FIG. 2.

Operation of the present switch involves sliding the resilient contactmember 27 in a direction parallel with the strips on the members, asindicated by the arrows in FIG. 2, whilst maintaining the members 27 and35 in engagement with one another. The two sections of each broken strip37 on the member 35 are electrically disconnected from one another orconnected together by a strip 29 on the member 27, according to therelative positions of the two members. Each end of each strip 37 on themember 35 has an external lead 45 soldered thereto. 1

To allow a manufacturer or user to construct any number of differentswitches according to his own circuit requirements it is convenient fora component manufacturer to supply him with composite resilient sheets,as shown in FIG. 2A. One of these sheets contains a series of mutuallyspaced, parallel strips 29 ofcopper on a base layer 31 of mylar. Eachstrip 29 is provided with a pair of raised, contact areas 33. The othersheet contains parallel strips 37 of copper on a base layer 39, eachstrip 37 being formed with one or more breaks 43. The manufacturer canthen crop each composite member to form two or more individual contactmembers, each having a predetermined number of strips 29 or 37 ofpredetermined length, with the raised areas 33 or breaks 43 atpredetermined positions lengthwise of the strips.

In the switch shown in FIG. 3 a second contact member 51 includes aresilient sheet comprising a series of copper areas 53 on a circularbase layer 55 of mylar. This sheet is adhesively secured to a supportingdisc 57. A first resilient contact member 59 is formed of a series ofmetal strips 61 on a base layer 63 of mylar each strip 61 having asingle raised contact area 65.

The disc 57 is mounted for rotation about the axis thereof and theresilient contact member 59 is arranged with the contact areas 65thereof extending radially of the disc 59 and biassed out of its naturalshape by engagement with the second contact member 51. Each strip 61 inthe resilient member is electrically connected to one or more of theremaining strips 61 by one or more copper areas 53 on the second member51, or disconnected from all remaining strips, according to the angularposition of the second member 51.

FIG. 4 shows a switch wherein a first, resilient contact member 71consists of a series of parallel copper strips 73 on a mylar base 75 andis supported by engagement of one end thereof in a clamp 77. A secondcontact member 79 consists of a resilient sheet having metal strips 81which is secured to a planar face of a supporting member 83.

The two members 71 and 79 are arranged with the metal strips 73 parallelwith and spaced from the strips 81 when the switch is in the offcondition. An operating member 85 engages the first member 71,intermediate the clamp 77 and raised contact areas 87 on this member,and upon operation to close the switch bends the first member 71 so thateach contact area 87 engages a strip 81 on the member 79. The distancethrough which the operating member 85 moves is slightly greater than theamount sufficient to cause each contact area 87 to contact thecorresponding strip 81 on the second member 79, and the contact area isthen maintained in engagement with the strip by virtue of the inherentresilience of the first member 71. An external lead 89 connected to oneend of each strip on each member.

It will be appreciated that in the above switches it is not es sentialfor the second contact member to be constructed from a resilientlaminate.

The raised contact areas on the resilient contact member can be formedby electroplating copper on to the copper strip or by securing anadditional element, suitably a rivet to the laminate rather than byembossing. Alternatively, the raised areas can be formed by etching awaypart of the remainder of the strips. To form a durable contact furthermetal may be electroplated on to the raised contact area. Suitably, theraised area is first plated with nickel and this in turn is plated withgold, to form hard gold.

Iclaim: I

1. A switching mechanism adapted to make and break a plurality ofelectrical connections, comprising a first member including a section ofthin flexible insulating material, a plurality of resilient strips ofelectrical conductors carried on said insulating section in spaced apartsubstantially parallel relationship so that said section and conductorsmay be flexed and the inherent resiliency of said strips tends to biassaid first member toward a relaxed condition, a second member having apredetermined pattern of conductive material thereon, said first andsecond members being disposed in operative relationship to make andbreak electrical connections upon relative movement therebetween, andthe inherent resiliency of said strips acts to hold said first member inbiased engagement with said second member.

2. The mechanism of claim 1 wherein spaced apart areas of said stripsare raised with respect to the remainder thereof, the conductors of saidsecond member are also a plurality of spaced apart and substantiallyparallel, and interrupted at portions along the length thereof, and saidspaced apart raised portions of said first strips are arranged toselectively bridge the interruptions upon relative movement of saidfirst and second members.

3. The mechanism of claim 1 wherein the second member is in the form ofa rotatable disc having a conductive pattern on the face thereof, saidfirst member is positioned with respect to said second member such thatsaid strips are flexed and the inherent resiliency thereof biases saidfirst member toward said disc.

4. The mechanism of claim 1 wherein the second contact member is formedwith a generally planar surface upon which the associated electricalcontact is provided and the mechanism is operated by relative movementbetween the contact members in a direction generally parallel with saidstrips.

5. The mechanism of claim 1 wherein the second member is a rotaryelement carrying contacts on a cylindrical surface thereof, andoperation of the mechanism is effected by rotation of said rotaryelement.

6. The mechanism of claim 1 wherein the second contact member includes arotary disc having the second contacts thereon on a planar face thereofand operation of the mechanism is effected by angular movement of thedisc.

7. The mechanism of claim 1 wherein the second contact member is aresilient material having a layer of electrically conductive material ona base layer of insulating material secured to a supporting member ofrigid construction.

first and second members being disposed in operative relationship tomake and break electrical connections upon relative movementtherebetween, means for urging said first member into engagement withsaid second member and flex said first member, and the inherentresiliency of said strips acts to move said first member from engagementwith said second member when the force of said means for urging isremoved.

1. A switching mechanism adapted to make and break a plurality ofelectrical connections, comprising a first member including a section ofthin flexible insulating material, a plurality of resilient strips ofelectrical conductors carried on said insulating section in spaced apartsubstantially parallel relationship so that said section and conductorsmay be flexed and the inherent resiliency of said strips tends to biassaid first member toward a relaxed condition, a second member having apredetermined pattern of conductive material thereon, said first andsecond members being disposed in operative relationship to make andbreak electrical connections upon relative movement therebetween, andthe inherent resiliency of said strips acts to hold said first member inbiased engagement with said second member.
 2. The mechanism of claim 1wherein spaced apart areas of said strips are raised with respect to theremainder thereof, the conductors of said second member are also aplurality of spaced apart and substantially parallel, and interrupted atportions along the length thereof, and said spaced apart raised portionsof said first strips are arranged to selectively bridge theinterruptions upon relative movement of said first and second members.3. The mechanism of claim 1 wherein the second member is in the form ofa rotatable disc having a conductive pattern on the face thereof, saidfirst member is positioned with respect to said second member such thatsaid strips are flexed and the inherent resiliency thereof biases saidfirst member toward said disc.
 4. The mechanism of claim 1 wherein thesecond contact member is formed with a generally planar surface uponwhich the associated electrical contact is provided and the mechanism isoperated by relative movement between the contact members in a directiongenerally parallel with said strips.
 5. The mechanism of claim 1 whereinthe second member is a rotary element carrying contacts on a cylindricalsurface thereof, and operation of the mechanism is effected by rotationof said rotary element.
 6. The mechanism of claim 1 wherein the secondcontact member includes a rotary disc having the second contacts thereonon a planar face thereof and operation of the mechanism is effected byangular movement of the disc.
 7. The mechanism of claim 1 wherein thesecond contact member is a resilient material having a layer ofelectrically conductive material on a base layer of insulating materialsecured to a supporting member of rigid construction.
 8. A switchingarrangement adapted to make and break a plurality of electricalconnections, comprising a first member including a section of thinflexible insulating material, a plurality of resilient strips ofelectrical conductors carried on said insulating section in spaced apartsubstantially parallel relationship so that said section and conductorsmay be flexed and the inherent resiliency of said strips tends to biassaid first member toward a relaxed condition, a second member having apredetermined pattern of conductive material thereon, said first andsecond members being disposed in operative relationship to make andbreak electrical connections upon relative movement therebetween, meansfor urging said first member into engagement with said second member andflex said first member, and the inherent resiliency of said strips actsto move said first member from engagement with said second member whenthe force of said means for urging is removed.